1. Field of the Invention
The present invention generally relates to a CMOS off-chip driver (OCD) and, more particularly, to a high-performance CMOS interface which generates shifted level voltage swings and is compatible emitter coupled logic (ECL).
2. Description of the Prior Art
High speed data transmission over long cable distances has been limited to bipolar differential circuits using emitter coupled logic (ECL) levels. With the advent of complementary metal oxide semiconductor (CMOS) field effect transistor (FET) technology, very high circuit densities are achievable. However, CMOS circuits do not have the small signal, high data rate capability of bipolar ECL circuits. Previous work in the area of CMOS ECL circuits demonstrated the ability to provide limited voltage swings using a single power supply. See, for example, U.S. Pat. No. 4,998,028 to Barbara A. Chappell et al. which discloses a circuit that is not applicable to standard cell logic methodology.